Question about number locks

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My dad has an attache case (is that how it's spelled?) whose three-number combination he has forgotten. I'm trying to open it but I'm not good enough at math to figure out how many possible combinations a three-number lock has. I tried starting from 0-0-0 and went progressively up. By which I mean, I went from 0-0-0 to 0-0-1, 0-0-2 and so on until I reached the 9-9-9 combinations. If I'm counting right, that was essentially 1,000 combinations. It still won't open. Before giving up and just breaking it open (the lock might just be busted, after all), I would like to ask if anyone is aware how many possible combinations a three-number lock has. My brother said, "Use the Factor 9 formula," which I can't remember anymore, but he explained was something like 9 times 8 times 7... times 1, then multiply the answer by three (I think; I've forgotten his exact words). Does anyone else have an idea? I don't want to think my patience would yield nothing but I really don't want to destroy it unless it's as a last resort.